High-performance solid-state supercapacitors based on graphene-ZnO hybrid nanocomposites

Abstract

In this paper, we report a facile low-cost synthesis of the graphene-ZnO hybrid nanocomposites for solid-state supercapacitors. Structural analysis revealed a homogeneous distribution of ZnO nanorods that are inserted in graphene nanosheets, forming a sandwiched architecture. The material exhibited a high specific capacitance of 156 F g−1 at a scan rate of 5 mV.s−1. The fabricated solid-state supercapacitor device using these graphene-ZnO hybrid nanocomposites exhibits good supercapacitive performance and long-term cycle stability. The improved supercapacitance property of these materials could be ascribed to the increased conductivity of ZnO and better utilization of graphene. These results demonstrate the potential of the graphene-ZnO hybrid nanocomposites as an electrode in high-performance supercapacitors.

Capacitive behaviour of functionalized carbon nanotube/ZnO composites coated on a glassy carbon electrode

“…As the scan rate increases from 10-500 mV/s, area under curve increases and the specific capacitance value decreases. This is because at lower scan rates electrolyte ions are completely diffused into the material and hence all the active surface of material can be utilized for charge storage whereas at high scan rates, diffusion limits the movement of electrolyte ions due to the time constraints and only the outer active surface is used for charge storage [3,56]. At very low scan rates, scan rate independent behavior of specific capacitance 20 may be expected.…”

“…FZ-1 composite exhibits the smallest R ct of 0.31 KΩ, indicating the optimal composition of CNTs and ZnO that lowers the inter-granular electronic resistance among active materials and the contact resistance between the electrode and the current collector [20,56]. FCNTs is very important to obtain good electrochemical performance.…”

Solvothermal synthesis of graphene–MnO2 nanocomposites and their electrochemical behavior

“…Figure 4(b-f) shows the CV curves of MnO 2, GM1, GM2, GM3 and GM4 electrodes respectively over a potential range of -1 to 1 V which still exhibited a nearly rectangular shape signifying good capacitive performance. It was observed that an increase in scan rate lead to an increase in the CV area of the elctrode reflecting good storage rate ability as reported by previous reports [35,45]. The specific capacitance (C s ) can be calculated from the CV curves by equation 2 below [35]:…”

“…The average energy density (E) and power density (P) of the electrochemical capacitors were calculated to further determine their electrochemical performance using the following equations [45]:…”

ZnO decorated graphene nanosheets: an advanced material for the electrochemical performance and photocatalytic degradation of organic dyes

“…Several methods have been carried out to produce graphene/ZnO and graphene/Mn 2 O 3 composites. Other researchers have also synthesized graphene/ZnO and graphene/Mn 2 O 3 , as they appear to be promising materials for pseudocapacitors due to their superior electrochemical performance, environmental friendliness, and lower production costs [5]. The present research is mainly focused on synthesizing Reduced Graphene Oxide (RGO) by using Hummer's method.…”